As the above-described valve opening/closing timing control device, JP 2015-78635A (Reference 1) discloses a technology in which a spool is coaxially disposed with a rotation axis, a relative rotation phase is controlled in an advance direction and a retard direction by operating the spool in a direction along the rotation axis, and thus, a lock mechanism is shifted to a locked state by setting the spool to an operation end in the advance direction and an operation end in the retard direction.
In Reference 1, a check valve is provided in a flow path through which a fluid is supplied to the spool, and thus, this check valve can prevent the fluid from flowing to a hydraulic pump side.
As described in Reference 1, the single spool is coaxially provided with the rotation axis of the valve opening/closing timing control device, and when controls of supplying and discharging the fluid with respect to an advance chamber and a retard chamber are performed by operating the spool, in a situation where the state is an unlocked state, for example, in a case where the fluid is supplied to the advance chamber when straddling a lock groove, a supply pressure of the fluid with respect to the valve opening/closing timing control device is decreased by supplying a working oil to the advance chamber, a lock release pressure acting on the lock mechanism decreases, and thus, it is considered that the lock mechanism is shifted to the locked state.
In the lock mechanism, a recessed portion is formed in one of a driving side rotator and a driven side rotator, a lock member which can engage with the recessed portion is supported by the other thereof, and an urging force generated by a spring by which the lock member engages with the recessed portion acts on the lock member. In the above-described configuration, in a case where an unlocked state of the lock mechanism is maintained, it is necessary to continuously supply the fluid to the lock member.
In a case where a valve unit is configured to include the single spool, an advance port communicating with the advance chamber, a retard port communicating with the retard chamber, and a lock port communicating with the lock member are disposed to be positioned so as to be close to each other. For example, in a case where the spool is operated to an advance position to perform an advance operation from a situation where the spool is positioned at a neutral position and a fluid pressure acts on the lock port, the fluid is supplied to the advance port, and thus, the fluid pressure of the lock port decreases. Therefore, it is considered that the lock member unintentionally engages with a lock recessed portion. Here, in a case where an intermediate lock mechanism is provided, it is necessary to change a phase across an intermediate lock recessed portion. Accordingly, compared with a configuration in which the most retarded lock mechanism or the most advanced lock mechanism is provided, a phenomenon of being erroneously shifted to a locked state easily occurs, and thus, it is necessary to prevent this phenomenon.
In order to suppress the above-described inappropriate operations, for example, it is also considered that a fluid pressure continuously acts on the lock mechanism even when a relative rotation phase is controlled by individually providing a phase control hydraulic valve for controlling a working oil supplied to or discharged from the advance chamber and the retard chamber and a lock control hydraulic valve for controlling the lock mechanism. However, in this configuration, two hydraulic valves are required, and thus, the number of parts increases, a configuration of an oil passage is complicated, and a size of the configuration increases.
Thus, a need exists for a valve opening/closing timing control device which is not susceptible to the drawback mentioned above.